Effects of manganese toxicity on leaf CO2 assimilation of contrasting common bean genotypes

Abstract

1997. Effects of manganese toxicity on leaf CO2 assimilation of contrasting common bean genotypes. -Physiol. Plant. 101: 872-880.Parameters related to leaf photosynthesis were evaluated in three genotypes of common bean {Phaseolus vulgaris L.) with contrasting tolerance to Mn toxicity. Two short-term studies in solution culture were used to assess the effect of excess Mn on CO2 assimilation in mature and immature leaves. Mn toxicity decreased total chlorophyll content only in immature leaves, with a consequent reduction of leaf CO2 assimilation. Mature leaves that showed brown speckles characteristic of Mn toxicity, did not suffer any detriment in their capacity to assimilate CO2, at least in a 4-day experiment. Stomatal conductance and transpiration were not affected by the presence of high levels of Mn in leaf tissue. Lower stomatal conductance and transpiration rates were observed only in leaves with advanced chlorosis. Differences among genotypes were detected as increased chlorosis in the more sensitive genotype ZPV-292, followed by A-283 and less chlorosis in the tolerant genotype CALIMA. Since CO2 assimilation expressed per unit of chlorophyll was not different between high-Mn plants and control plants, we conclude that the negative effect of Mn toxicity on CO2 assimilation can be explained by a reduction in leaf chlorophyll content.

Characterization of the tolerance to excess manganese in four maize varieties

“…4), and support data reported previously for other crop species (Ohki 1985;Nable et al 1988;Kitao et al 1997). The photosynthetic activity and chlorophyll content of Mn-stressed plants have been used as suitable criteria for screening Mn tolerance in Triticum aestivum (Macfie and Taylor 1992;Moroni et al 1991), Phaseolus vulgaris (González and Lynch 1997) and in deciduous broad-leaved tree seedlings (Kitao et al 1998). Electrolyte leakage as a consequence of the loss of membrane integrity can also be used as a marker to measure cell membrane functional status under stress conditions (Almeselmani et al 2006).…”

“…The photosynthetic activity and chlorophyll content of Mn‐stressed plants have been used as suitable criteria for screening Mn tolerance in Triticum aestivum (Macfie and Taylor 1992; Moroni et al. 1991), Phaseolus vulgaris (González and Lynch 1997) and in deciduous broad‐leaved tree seedlings (Kitao et al. 1998).…”

Early manganese‐toxicity response in Vigna unguiculata L. – a proteomic and transcriptomic study

“…Enrichment of Mn in the chloroplast was reported for common bean [20] and rice [21]. In common bean, this was accompanied by a decrease of the chlorophyll content and by a reduction of CO 2 assimilation rates [20,22,23]. Reduced CO 2 assimilation upon Mn stress was also reported for tobacco [24,25] and reduced chlorophyll content for wheat [26].…”

A Critical Review on the Multiple Roles of Manganese in Stabilizing and Destabilizing Soil Organic Matter

“…Mn­(II) species in litter are oxidized to insoluble Mn­(III/IV)-oxides during decomposition, facilitating their accumulation in surface soils. ,, Many plants accumulate Mn in linear proportion to the quantity of soluble and exchangeable Mn­(II) in soil . As such, foliar Mn concentrations often exceed nutritional requirements, resulting in oxidative stress and impaired photosynthesis in sensitive plant species (e.g., sugar maples). ,− At the ecosystem-scale, Mn toxicity can lead to declines in certain plant types where soil Mn is highly phytoavailable. For example, increases in Mn­(II) solubility driven by chronic nitrogen deposition led to the decline of forbs in a temperate steppe ecosystem .…”